With development of modern society and people's awareness of environmental protection, more and more equipment use a rechargeable secondary battery as a power source, such as mobile phones, laptops, electric tools, electrical automobiles and energy storage power stations, which provides a broad space for application and development of the rechargeable secondary battery. Such electrical automobiles and energy storage power stations generally require power batteries with high capacity as the power source. These power batteries should also have good safety and a long cycle life in addition to high capacity, so as to meet an operation standard and meet people's requirements.
An overcharge protection device of a lithium-ion battery mainly adopts a deformable safety valve, the deformable safety valve comprises a short-circuit conductive plate and a deformable plate, when the battery is overcharged, the overcharge protection device realizes short-circuit between a positive electrode and a negative electrode to release battery cell energy through external short-circuit, so as to avoid safety accidents, but aluminum is mainly adopted as materials of the short-circuit conductive plate and the deformable plate in the prior art, as aluminum is easily oxidized into aluminum oxide in air, contact resistance is very large, the aluminum plate of the deformable safety valve is easily molten through at the moment of short-circuit, and simultaneously sparks possibly to set fire to electrolyte in the battery cell, which is very dangerous, and makes the deformable safety valve fail to work.